worried about TMA bust

[buzzc152]

A week or so back I was flying low level in the Biggin ATZ on their QFE (994 I think it was). Upon departing the area to the south east I climbed to 2200' but failed to roll on the QNH so was actually at about 2650, ie inside the LTMA. I realised pretty quickly and descended down again........... I was probably in the LTMA for 30 secs or so......maybe a minute at the most.

Now I know busts of the TMA base are a failrly common occurance but this has been nagging at the back of my head for a week now. Would Thames Radar/London City be likely to a have filed a report ? Would the CAA be likely to pursue such a bust if they had the aircraft details (which I'm sure could be easily obtained) ?

Any advise on what to do?

Buzz

ps, whilst I'm 100% at fault, I'm a little miffed Biggin App didn't pass me the QNH as I left their area...... if they had I certainly wouldn't have made the mistake I did.

[LondonJ]

I wouldn't worry about it too much, these things are fairly regular. A call to the appropriate ATC unit is always a good idea after landing, just apologise and accept responsibility and for the most part it goes no further (they don't want to deal with paperwork anymore than you do).

If you do feel it necessary file an MOR with the CAA, it only starts getting more serious when you cause Atc to have to shift aircraft around and in this case they would submit a 939 form and the caa is compelled to investigate further.

Not sure on technicalities of London TMA but I assume there is a buffer zone of a few hundred feet above 2500 to allow for exactly this.

If you are really worried just phone atc (maybe someone can provide a number?) and check.

J

[eyeinthesky]

If anyone had filed an MOR, you would have heard about it by now!

I should chalk it up to experience. What have you learnt? That you should ensure you follow correct altimeter setting procedures and maintain situational awareness?

Failure to set the correct altimeter setting is one of the biggest causes of level busts inside and outside controlled airspace. They can result in anything ranging from a red face to a collision between two aircraft. Just remember that the only thing keeping you apart from another collection of aluminium is 1000ft of air. That is approx 300 yards. Next time you go past Gatwick or Heathrow, take a look at how big a 747 looks from 300 yards away. It will probably help you to remember to do everything you can to make sure that distance doesn't get any less, and correct altimeter setting is part of this.

LondonJ:

Quote
Not sure on technicalities of London TMA but I assume there is a buffer zone of a few hundred feet above 2500 to allow for exactly this.
Unquote

That is a VERY dangerous assumption. IFR traffic can be operating to within 500ft of the base of CAS (eg 3000ft where the base is 2500ft). For the reasons given above, you do not want that to be any less. The ONLY buffer you should use is that between your present altitude on the QNH relevant to the airspace (in this case the London QNH) and the base altitude of CAS. If you need a 200ft buffer, then fly at 2200 ft!

[Cusco]

)Buzzc152 said



What should I do?



Keep your gob shut

Cusco

(been there, done that,, got the CAA letter

[Spitoon]

A simple question - were you squawking mode C?

While busting airspace is to be avoided, if you weren't squawking C no one is likely to know.

[fireflybob]

If we only flew on QNH like they do in the USA then perhaps this type of airspace bust would be far less common?

[big.al]

...if you weren't squawking C no one is likely to know...

Which reminds me of a topic which came up a while ago, to which I can't remember the answer. I ought to know this really but...

... does Mode C transmit the altitude based upon the current altimeter setting or based upon 1013? I assume that most transponders in simple a/c are not tied in to the altimeters - what would it read given that the C172 I fly has two of them?

In Buzz's example a difference of 450 feet is approx. 15mb. So at a QFE of 994 we assume a QNH of around 1009. If the Mode Charlie is based upon 1013 would the read out on the ATC display have actually been 2770 (i.e. 2800 ft..?).

Cheers!

[fireflybob]

Mode C - a/c equipment always sends back vertical position of a/c based on 1013 mb.

[AlanM]

I wasn't in on Thames last week - so cannot actually comment on your situation but as others have said, it is unlikely that any action has been taken if you have heard nothing.

We get traffic at 2800 all the time under the TMA around Biggin (one today 15 E of LCY at 3200)

Now, if you were at 2650 under the ILS for 28 at LCY and the inbound over the top was at 3000feet and took a TCAS climb paperwork would have to be filed and you would probably have been closely followed back to your unit for identification.

As long as you have learnt from it. And if you don't have your Mode C on, other traffic with TCAS outside CAS (Posh helis/bizjets etc) won't get any TCAS avoiding action on you - so leave it on I would suggest.

Oh - and the London QNH is entered into the Radar equipment and shows on our screens - meaning that the Mode C we see is adjusted accordingly from what has been received by the radar.

[Monocock]

As long as you have learnt from it.

This seems to me to be the key to this.

Nobody got hurt and you are clearly worried about it enough to know that you won't do it again.

I'm sure if everyone who did it was as concious of it and concerned as you are then we would all be a lot safer. I'm sure the majority of the time that it happens the person involved doesn't even know about it and that is FAR more worrying.

BuzzC152, move on mate. It's happened and you have CHIRPED it which is good.

Safe flying....:ok: